Innovation of nano-hydrogels loaded with amelogenin peptide and hydroxyapatite nano-particles for remineralisation of artificially induced white spot lesions

Abstract

BackgroundWhite spot lesions are a common side effect of fixed orthodontics. This study investigates chitosan-based hydrogels using amelogenin peptide as a scaffold to facilitate hydroxyapatite nanoparticle attachment, assembly, and organisation, aiding in enamel remineralisation. Materials and methodsThree groups were prepared to carry out remineralisation experiments after creating artificial white spot lesions on extracted 1st premolars. The first group served as a control with no treatment, while the experimental groups were treated with either amelogenin peptide/chitosan hydrogel or amelogenin peptide + hydroxyapatite/chitosan hydrogel. Remineralisation was conducted for three weeks. The interaction between amelogenin peptide and hydroxyapatite nanoparticles was evaluated using TEM, UV–Vis, FTIR, zeta potential, and Raman spectroscopy. Remineralisation potential was assessed through enamel microhardness, fluorescence, and XRD. Surface characteristics of demineralised and remineralised enamel were examined by SEM at different magnifications, and chemical compositions were analysed using an EDX analyser. one-way ANOVA and Tukey HSD post hoc multi-comparison tests were performed to find statistical differences between groups. A pairwise comparison was performed to examine if there were significant differences within each group. Significant differences were considered at a P < 0.05. ResultsThe results demonstrated that amelogenin peptide adsorbs onto hydroxyapatite. TEM images revealed the self-assembly of peptide nanoparticles and their adsorption onto hydroxyapatite nanoparticles. UV–Vis spectroscopy, FTIR spectroscopy, Zeta Potential, and Raman Spectroscopy confirmed the binding between amelogenin peptide and hydroxyapatite. The novel hydrogel significantly improved the microhardness and fluorescence values of demineralised enamel. Energy-dispersive X-ray Spectroscopy and X-ray diffractometry revealed the formation of new hydroxyapatite crystals on demineralised enamel, with a calcium-to-phosphorus ratio comparable to natural enamel hydroxyapatite. Structural analysis via SEM showed improved surface texture with the occlusion of demineralised surface porosities. Overall, the hydrogel enhanced hardness, fluorescence, morphology, and chemical composition compared to demineralised enamel. ConclusionsChitosan-based hydrogels provide a promising remineralising strategy that bio-mimics natural enamel regrowth.